Electrical heater



Oct. 16, 1928. 1,687,858

- F. c. CURTIS ELECTRICAL HEATER Filed June 6 1927 Patented 2 Oct. 16, 1928.

UNITED STATES.

I 1,687,858 PATENT OF FREDERICK CHARLES CURTIS, OF LONDON, ENGLAND.

ELECTRICAL HEATER.

Application filed June 6, 1927-, Serial No. 196,968, and in Great Britain July 9, 1926.

This invention relates to electric tubular heaters applicablefor heating curling tongs and the like, and has for its object to provide an efficient heater. of simple and durable con struction. V

In this type of heater a resistance wire i wound round the outside of a tube adapted to receive the tongs. V

The present invention consists of a tubular electric heater comprising a tube consisting of two sectionsone of which contains the heating element while the other is provided with one or more openings or perforations. Both sections of the tubular element are preferably integral and supported concentrically in a casing.

The perforations in the tube may be in the form of slots or of any other desired shape.

. A manner of carrying out the invention is illustrated by the accompanying .drawing whereinFigure 1 is a partly sectional elevation, Figure 2 is a transverse section through 22 of Figure 1, and Figure 3 is a sectional plan of the device through 33 of Figure 1.

In these drawings 49 andi l are the two sections of a tubular element of which the base member is a metal tube, the section 4? having an outer tube or wrapping a of mica or other suitable material on which is wound a coil of resistance wire 5 coated with a fire-proof composition or cement, the ends of the coil being continued as leads 6 and 7 The bared ends of the leads 6 and 7 are fixed in projections 8 and 9 extending from metal sockets 10 and 11 fixed in a plug 12 of insulating material in the usual way, the plug 12 being of the kind provided with a screwed cap 13 of insulating material. In the sockets 10 fit pins 14: of a disconnectable plug provided with electric supply connecting leads 15 and 16 in the usual manner.

The coil 5 of the section 4* of thetube' is coated with asbestos or other suitable heat resisting material.

The outer end of the section 1 of the tube is supported in a disc 17 of asbestos or other suitable material secured to a sheet metal end 18 of the casing and to the plug 12 by screws 19, while the outer end of the section 1 of the tube is supported in a disc 21 of asbestos secured to a sheet metal end 22'by rivets 23.

' The section 42 of the tubular element is provided with longitudinal perforations 24 arranged to extend to near the open end 25 of the tubular element through which the tongs or other'devices to be-heated are passed into the heating section 4301': the apparatus.

, The end plates 18 and 22 are connected to a base 26, of suitable material, and between these end plates and fitting on the discs 17 and 21 is a tube 27 of asbestos or other suitable material surrounded by a thin metal cylindrical casing 28 secured by screws 29 toprojections 30 extending from the end plates 18 and 22. The casing 28 does not fit closely on the tube 27 of insulating material and so forms an additional heat insulating jacket of air. The

cylindrical casing 28 is provided with a spirally wound metal wire handle 31.

By means of the improvementsaccording to the present invention less current than heretofore is consumed in heating up an article owing to the better utilization of the heat generated. Furthermore such improvements havet-he additional advantage in that damage tothe heater by overheating is obviated, the apertures or slots forming a vent for the rapid dispersal of the heat generated, when the tongs or other article to be heated is withdrawn for use.

What I claim' and desire to secure by Letters Patent is:

1. An electric heater comprising in combination a resistance coil, an inner tube for receiving the article to be heated, an outer concentric tube of insulating material and a casing, the resistance coil being wound on one section of the inner tube while the other section is provided with means for freely conducting heat from the airspace outside to the inside of the inner tube, without communicating with the casing.

2. An electric heater in, accordance with claim 1, wherein an annular nonconducting air space is formed between the outer tube and the casing.

3. An electric heater in accordance with claim 1, wherein the section of the inner tube on which the coil is not wound is provided with a multiple of circumferentially spaced perforations arranged to allow of free conductivity of heat by the contained air from the out-ertothe inner tube, independently of the casing. I

1. An electric heater in accordance with claim 1, wherein the coilis a single layer coil extending from an insulated end common to both the inner and outer tubes and carrying the terminals, the other end of the coil terminating at a portionofthe tube provided with a series of circumferentially spaced openings While the other end of the perforated portion is supported in the central aperture of an insulated end for the outer tube.

5. An electric heater comprising three coneentrically supported cylindrical tubes separated by air spaces, the inner tube being perforated along a section of its length and a resistance coil wound on the other.

6. An electric heater comprising in combination, an outer cylindrical casing of thin metal supported in a standard, a smaller tube of insulating material having ends of insulating material, and a smaller central tube of thin metal perforated along one portion of its length and Wound on the other section of its length With a single layer of a resistance coil insulated on its inner and outer surfaces, the central tube being supported on one end in a recess in a disc forming one insulated end of the insulated tube and carrying the terminals, the central tube being supported at its other end in an opening in the other insulated end of the insulated tube, concentric air spaces being formed between the three tubes.

In Witness whereof I aflix my signature.

FREDERICK CHARLES CURTIS. 

